Safety means for internalcombustion engines



1950 L. D. THOMPSON 2,518,400

SAFETY MEANSFOR INTERNAL-COMBUSTION ENGINES Filed July 23, 1948 ATTORNEYPatented Aug. 8, 1950 SAFETY-MEANS For. INTERNAL-- COMBUSTION ENGINESLionel 1). Thompson, Beloit, Wis., assignor to.

Fairbanks, Morse & 00., Chicago, 111. a corporation of IllinoisApplication uly 23, 1948; Serial No. 40,228

. 1 This invention relates to safety means for internal combustionengines, and is particularly concerned with means for insuring safeopera-- tion of dual fuel engines.

The subject of this invention is closely related with the type of dualfuel engine shown and described in a prior application for patent ofClarence H. Schowalter, filed January 11, 1947,.

and bearing Serial No. 721,549. In that application a control, systemfor dual fuel engines has been described. In its essential disclosure,the

engine is provided with a liquid fuel pump having a source of supplyunder at least a predetermined minimum head pressure to assure anadequate feed. There is also a gaseous fuel supply conduit in which acontrol valve islocated, the valve being constantly biased in a closingdirection and being operated to an open position by means of a motordevice which is associated with engine control system. This lattercontrol system is arranged to permit engine operation on liquid fuelalone or on gaseous fuel with a reduced charge of the liquid fuelsupplied to the combustion chamber for purposes of initiating the propercombustion of the gaseous fuel. A more complete knowledge of the engineoperation may be had by reference to this prior application.

The present invention has as its principal object the provision ofsafety means functionally related with the liquid and gaseous fuelsupply systems of the engine so that an improper sup- 1 7 Claims. ((21.123-27),

engine, with the present safety device shown in sectional elevation.

In the drawing, the engine is represented as of two-cycle Diesel typhaving a cylinder J3 provided with suitable air inlet and scavengingports controlled by the piston I!) connected to a crankshaft in theusual manner. The cylinder head structure 2! is formed to receive aliquid fuel injection nozzle 22, a gaseous fuel admission valve 23 andan air starting valve 24. The air start valve 24 forms no part of thisinvention and has been shown in fragmentary part only. The gaseous fuelvalve 23 is conventionally operated through an engine driven cam 25 andcooperating push rod 26 and rocker 21, the latter being carried by asuitable bracket 28.

The liquid fuel supply system for the engine comprises a supply header29 receiving the fuel from a suitable source (not shown) under a preply.in one of the liquid fuel systems will cause a shut-down in the supplyfrom the gaseous fuel system and result in stoppage of the engine beforeany great amount of gaseous fuel can accumulate in the engine or itsexhaust manifold to create a dangerous and explosive residual charge.

It is also an object of this invention to provide a simple, positiveoperating safety device for dual fuel engines which is responsive solelyto a pressure drop of a predetermined order in the liquid supply systemfor effecting a stoppage of the engine by interrupting the supply offuel from the gaseous fuel supply system, it beingparticularlydetermined minimum head pressure which will provide for anadequate supply to the inlet line 30 of a fuel pump 3!. The pump 3| isconnected to the injection nozzle 22 by the high pressure feed line 32.Pump 3| is provided with a control member 38 for effecting variations inthe fuel delivery, and member 33 is longitudinally displaced under thecontrol influence of an angularly movable lever system 34. The member 33is spring urged against the lever system 34 and rotates the usual pumpdisplacement piston (not shown) after the manner of the'well known Boschtype pump. Lever system 34 includes a principal arm 35 fixed on thecontrol shaft,

' schematically represented by the dashed line 36,

ondary arm ,31 is independently pivoted but is,

cam controlled to assume a setting capable of maintaining the pumpmember 33 at its minimum fuel delivery or pilot fuel injection setting.This pump control is more fully discussed in the prior application forpatent of Clarence H. Schowalter. Control shaft 36 is rotated inresponse to the action of a governor 38 during the period when the arm35 is effective to regulate pump delivery in accordance with thegovernor speed response. It should be understood that the pump 3| andits associated control lever system 34 is shown herein by way of exampleonly, and

-that other types of fuel pumps can be substituted therefor withoutaffecting the intended results.

The gaseous fuel supply system for the engine includes a gaseous fuelconduit 43 connected to a valve chest ll, and a header l2 leading fromthe chest 4| to a branch line 43 which, in turn,

opens into the cylinder head 2| adjacent the gaseous fuel admissionvalve 28. The valve chest 4| contains a valve 44 which is subject to thecontrol action of the governor 38 through the control shaft 36. Conduit46 is equipped with a control valve 45 in which the valve element 46 isconstantly urged in a closing direction by a spring element 41, and isoperated in an opening direction by motor means 48.

The motor means 48 constitutes one part of a releasable holding means orsystem Operatively associated with the control valve 45. This systemincludes a manual control cam 58 regulating the position of the plungerin a master relay 52, a responsive relay 53 having a plunger 54 which isresponsive to an engine over-speed governor device 55 through amechanical lever system 56, a system of fluid pressure and drain pipes,and an engine driven pump 51. The pump 5'! draws hydraulic fluid fromthe sump 58 and delivers it into line 58 leading to the upper zone ofthe master relay 52. From the latter relay a drain line 60 extends tothe sump 58, and a pressure line 6| leads to the safety device,generally indicated at 62. From the device 62 a pressure line 63 leadsto the responsive relay 53, and a line 64 connects between the relay 53and the motor means 48. Relay 53 is provided with a normally closeddrain line 65 (as shown) which connects into a second drain line 66, thelatter drain extending between the device 62 and sump 58.

The safety device 62 comprises a cylindrical housing 68, a plungerelement 69 slidably disposed in the housing to define an annular chamberbetween its opposite pistons 1| and 12, a spring 13 and retainer cap 14,and a tappet element slidably disposed in the end of the housing 68opposite the spring 13. Operatively associated with the device 62 is apiston and cylinder assembly 16. This assembly has its cylinder 11axially aligned with the housing 68 so that a slidable tappet element 18is conditioned to engage the head of tappet 15. The tappet 18 isactuated by a piston element 19 cagedjn the cylinder 11 by the cap 88.Assembly I6 is connected by a pressure line 8| in the cap 80 with theliquid fuel supply header 28 so that the piston 18 is constantly subjectto the predetermined minimum pressure and is urged to the positionshown. In such position, the plunger 69 of the device 62 is displacedagainst its spring 13 so that the upper piston ll uncovers fluidpressure line 6| and the lower piston element I2 covers the drain line66. So long as the predetermined minimum supply pressure prevails in theliquid fuel header 29, the device 62 will be held in the setting shown,since this pressure is sufficient to overpower the loading spring I3.Any decrease of this pressure will immediately allow spring I3 tooverpower the piston 19 and displace the plunger 69 so that line 6| willbe closed and drain 66 will be opened. The line 63 to relay 53 will notbe afiected and consequently may act as a drain line from the motormeans 48 to release the same for valve closing action by its spring 41.-

In the drawing, the system has been shown at engine starting with thepump 3| delivering liquid fuel and the master relay 52 conditioned bythe control cam 50 to prevent opening of the gaseous fuel control valve45. At this time, it will be noted that the safety device has attainedits proper setting so as not to interrupt fluid pressure actuation ofthe motor means 48. When it is desired to operate the engine as a dualfuel engine, the control cam 50 is rotated counter clockwise 90 degreesto bring the low zone 82 of the cam over the master relay plunger 5| andenable the plunger to rise under the spring load thereon. Theplunger IIwill close drain line and connect the pressure line 58 with line 6'! sothat fluid pressure is transmitted to the chamber 10 of device 62 andinto line 63. Relay 53, being held by the overspeed governor 55 asshown, will permit the pressure to act on the motor means 48 in adirection to open the control valve 45 in the gaseous fuel supplyconduit 40. Thus the conversion to dual fuel operation of the engine iscompleted, and the governor 38 will regulate valve 44 in the valve chest4| to supply gaseous fuel as required. At the same time the secondarylever 31 at the fuelpump will assume control thereof to maintain theproper supply of the liquid fuel for pilot ignition purposes.

Should the liquid fuel header pressure drop below the minimum desired,the spring 13 in the safety device 62 will immediately overpower thepiston 18 and displace the plunger 68 to interrupt the fluid pressureline 6| and open drain line 66. This latter action releases the valvemotor means 48 by draining away the pressure fiuid through the relay 53,line 63, and chamber 10, to line 66. Once released, the spring 41immediately closes the control valve 46 and prevents further supply ofthe gaseous fuel. In this manner, the engine is prevented fromaccumulating a quantity of combustible matter in the exhaust manifoldwhich could become explosively dangerous at the next starting attempt.

Only a single form of the invention has been shown and described, but itshould be understood that changes, and substitution of parts andelements may be made herein without departing from the spirit and fullintended scope of the invention as defined by the following claims.

I claim:

1. In a. dual fuel internal combustion engine, a gaseous fuel inletconduit, a normally closed valve controlling the conduit, a liquidfuelpump connected to the engine and supplied with liquid fuel under atleast a minimum head pressure, means for releasably holding said valveopen'to supply gaseous fuel during normal dual fuel operation of theengine, and a device responsive to liquid fuel supply head pressure forrendering said releasable holding means effective to open said valve,said device being immediately operable upon liquid fuel supply headpressure drop below the minimum to release said holding means and permitvalve closure.

2. In a duel fuel internal combustion engine, a gaseous fuel inletconduit, a valve controlling said conduit, means constantly urging saidvalve to close the conduit, a liquid fuel pump connected to the engineand supplied with liquid fuel at a minimum predetermined head pressure,means for releasably holding said valve open to supply gaseous fuelduring normal dual fuel operation of the engine, and -a deviceresponsive to liquid fuel head pressure for rendering said releasableholding means effective toopen said valve, said device being operableupon a reduction of the minimum liquid fuel supply head pressure torelease said holding means and permit valve closure by said urgingmeans.

3. In a duel fuel internal combustion engine,

a liquid fuel pump connected to the engine and supplied with liquid fuelunder at least a minimum pressure, a conduit connected with the enginefor supplying a different fuel thereto, a valve controlling saidconduit, means for releasably holding said valve open to supply fueldurfuel supply for rendering said releasable holding means effective toopen said valve, said responsive means being operable upon a liquid fuelsupply pressure drop below said minimum to release said holding means,and means immediately operable upon release of said holding means toclose said valve.

4. In a duel fuel internal combustion engine, a liquid fuel pumpconnected to the engine and supplied with liquid fuel under at least aminimum pressure, a conduit connected with the engine for supplying adifferent fuel thereto, a conduit control valve normally closing theconduit, fluid pressure holding means for maintaining said valve openduring normal dual fuel operation of the engine, means responsive-toliquid fuel supply pressure for rendering said holding means effectiveto open said valve, said responsive means being operable upon a decreasein the minimum fuel supply pressure to release said holding means andenable valve closure of said conduit.

5. In an internal combustion engine, a fuel pump connected with theengine and supplied 7 with a liquid fuel, a'conduit connected with theengine for supplying a different fuel thereto, a valve in said conduitand acting to close the conduit at all times, means for releasablyholding said valve open to effect supply of the different fuel and thusdetermine engine operation with both said fuels, said releasable holdingmeans including a device normally movable in a direction to release saidholding means and permit valve closure, but movable in a reversedirection to effect valve opening action, and means responsive to thesupply of liquid fuel for movin said device in its reverse direction toeffect valve opening action.

6.- In a duel fuel engine, a first fuel supply system for the engineincluding a pump, a second fuel supply system for the engine including acontrol valve, fluid pressure means connected with said control valvefor releasably holding said control valve open during normal dual fuelengine operation, a safety device connected with said releasable holdingmeans and with said first fuel system, said device being operable inresponse to a predetermined decrease in the supply pressure of saidfirst fuel system for releasing said valve holding means, and means toclose said control valve immediately upon release by said device.

'7. In an internal combustion engine, a liquid fuel supply pumpconnected to the engine and supplied with liquid fuel at a predeterminedminimum pressure, a gaseous fuel supply conduit leading to the engine, acontrol valve in said conduit, means constantly urging said valve intoconduit closing position, fluid pressure operated motor means connectedwith said valve for opening the latter, a fluid pressure system for saidmotor means, a relay connected in said pressure system and normallyoperable to release the fluid pressure at said motor means for closureof said control valve, and means responsive to the maintenance of saidpredetermined liquid fuel supply pressure for operating said relay topermit operation of said motor means in a valve aopening direction, saidlast means having a connection with the liquid fuel supply whereby upona decrease in the minimum supply pressure of liquid fuel said relay willrelease the fluid pressure to said motor.

LIONEL D. THOMPSON.

REFERENCES CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS Number Name Date 1,858,824 Heidelberg May 17, 19322,409,611 Bodine Oct. 22, 1946 FOREIGN PATENTS Number Country Date404,612 Germany Oct. 21, 1924

